The decision to raise the terror level from 'substantial' to 'severe' is based on the latest intelligence

The UK terror threat level has been raised to 'severe' in response to IS activity in Iraq and Syria

The terror threat to the UK has been raised from substantial to severe just a week before the Nato Summit starts in Wales, Home Secretary Theresa May has announced.

This means that a terrorist attack is “highly likely”, although Mrs May stressed that there is no information to suggest an attack is imminent.

Prime Minister David Cameron today said the terror group seizing lands in Syria and Iraq, Islamic State, poses a "greater and deeper threat to our security than we have known before".

Ms May said: “The Joint Terrorism Analysis Centre (JTAC) is responsible for setting the national threat level. That informs the decisions of security professionals across the public and private sectors about the appropriate level of security in place across the United Kingdom.

“JTAC’s judgements about that threat level are made on the basis of the very latest intelligence and are independent of ministers.

“JTAC has today raised the threat level to the UK from international terrorism from SUBSTANTIAL to SEVERE. That means that a terrorist attack is highly likely, but there is no intelligence to suggest that an attack is imminent.”

Sir Bernard Hogan-Howe, the UK’s most senior police officer, said Scotland Yard is prepared for an influx in case a swathe of homegrown extremists decide to return at the same time.

In a statement released today, Mrs May said: “The increase in the threat level is related to developments in Syria and Iraq where terrorist groups are planning attacks against the West. Some of those plots are likely to involve foreign fighters who have travelled there from the UK and Europe to take part in those conflicts.

“The first and most important duty of government is the protection of the British people. We have already taken steps to improve our powers and increase our capabilities for dealing with the developing terrorist threats we face. That process will continue and the British public should be in no doubt that we will take the strongest possible action to protect our national security.

“We face a real and serious threat in the UK from international terrorism. I would urge the public to remain vigilant and to report any suspicious activity to the police.”

National Policing Lead for Counter-Terrorism Assistant Commissioner Mark Rowley said: “We need communities and families to bring to our attention anyone they perceive may be vulnerable, a danger or escalating towards terrorism. Anyone with information is urged to contact the Anti-Terrorist Hotline on 0800 789 321.

“From this afternoon we will begin to increase our levels of visible patrols and implement other security and protection measures. We will also build on existing community relations to provide reassurance and seek their support and assistance in keeping the UK safe.”

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